Calendar-Kanban or Kanban-Calendar App

like trying to enhence and go modern, have it in one and reduce needed updated calendar, task and kanban apps, i had the idea to look for a combined calendar-kanban app.
best open source and widely used, maybe even with huge community, but not neccesairly.
the option show task in calendar is also nice idea.
one can get the most of it if you can use kanban and have on the other hand appointments in view.
i'm not sure if one got the obviouse idea.
it would be the solution, as we have here maybe 20apps for it, but no breakthrough, a longtail.
enjoy your feedback, ideas, tips.
lets find a gamechanger!
thx